US20150298728A1 - Power-steering device - Google Patents
Power-steering device Download PDFInfo
- Publication number
- US20150298728A1 US20150298728A1 US14/646,803 US201314646803A US2015298728A1 US 20150298728 A1 US20150298728 A1 US 20150298728A1 US 201314646803 A US201314646803 A US 201314646803A US 2015298728 A1 US2015298728 A1 US 2015298728A1
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- Prior art keywords
- rotor
- steering device
- power steering
- input shaft
- stator
- Prior art date
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/09—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by means for actuating valves
- B62D5/091—Hydraulic steer-by-wire systems, e.g. the valve being actuated by an electric motor
- B62D5/092—Hydraulic steer-by-wire systems, e.g. the valve being actuated by an electric motor the electric motor being connected to the final driven element of the steering gear, e.g. rack
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/062—Details, component parts
- B62D5/064—Pump driven independently from vehicle engine, e.g. electric driven pump
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/08—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by type of steering valve used
- B62D5/083—Rotary valves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/10—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by type of power unit
- B62D5/12—Piston and cylinder
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/10—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by type of power unit
- B62D5/14—Rotary motor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
- B62D5/22—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for rack-and-pinion type
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
- B62D6/002—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels
- B62D6/003—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels in order to control vehicle yaw movement, i.e. around a vertical axis
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C35/00—Rigid support of bearing units; Housings, e.g. caps, covers
- F16C35/04—Rigid support of bearing units; Housings, e.g. caps, covers in the case of ball or roller bearings
- F16C35/06—Mounting or dismounting of ball or roller bearings; Fixing them onto shaft or in housing
- F16C35/063—Fixing them on the shaft
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C35/00—Rigid support of bearing units; Housings, e.g. caps, covers
- F16C35/04—Rigid support of bearing units; Housings, e.g. caps, covers in the case of ball or roller bearings
- F16C35/06—Mounting or dismounting of ball or roller bearings; Fixing them onto shaft or in housing
- F16C35/067—Fixing them in a housing
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/28—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
- H02K5/173—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using bearings with rolling contact, e.g. ball bearings
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
- H02K5/173—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using bearings with rolling contact, e.g. ball bearings
- H02K5/1732—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using bearings with rolling contact, e.g. ball bearings radially supporting the rotary shaft at both ends of the rotor
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/06—Means for converting reciprocating motion into rotary motion or vice versa
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D1/00—Couplings for rigidly connecting two coaxial shafts or other movable machine elements
- F16D1/06—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for attachment of a member on a shaft or on a shaft-end
- F16D1/08—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for attachment of a member on a shaft or on a shaft-end with clamping hub; with hub and longitudinal key
- F16D1/0876—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for attachment of a member on a shaft or on a shaft-end with clamping hub; with hub and longitudinal key with axial keys and no other radial clamping
Definitions
- the present invention relates to a power steering device for hydraulically assisting a driver's steering force and, more particularly, to a power steering device having a hydraulic control rotary valve driven by a motor to perform an automatic steering function.
- Patent Document 1 There is conventionally known a power steering device with an automatic steering function as disclosed in e.g. Patent Document 1.
- This power steering device is configured as a rack-and-pinion type hydraulic power steering device including an input shaft coupled to a steering wheel, an output shaft relatively rotatably coupled to the input shaft through a torsion bar, a rotary valve arranged at a position between the input shall and the output shaft on the outer circumference of a base end portion of the input shaft and a hollow motor arranged on the outer circumference of a front end portion of the input shaft.
- the rotary valve is opened in response to a driver's steering torque so as to generate a steering assist torque during normal operation mode.
- the rotary valve is opened by the application of a drive torque of the hollow motor under the control of an ECU so as to generate a steering assist torque for automatic steering operation.
- Patent Document 1 Japanese Laid-Open Patent Publication No. 2005-69767
- the above conventional power steering device has a problem of poor assembling workability because the hollow motor and the device body are integrated to each other. This results in a deterioration of productivity and a steep rise of manufacturing cost.
- the present invention has been made to provide a power steering device having improved assembling workability.
- a power steering device comprising: an input shaft rotated in response to steering operation of a steering wheel; an output shaft coupled to the input shaft through a torsion bar; a power cylinder having a pair of hydraulic pressure chambers defined by a piston to generate a steering assist force based on hydraulic pressures in the hydraulic pressure chambers; a rotary valve that selectively supplies hydraulic fluid from an external hydraulic pressure source to the pair of hydraulic pressure chambers in accordance with relative rotation of the input shaft and the output shaft; a hollow motor arranged to surround at least an axial portion of the input shaft and control rotation of the input shaft based on vehicle driving conditions; and input-shaft-side and rotor-side engagement parts arranged between an outer circumference of the input shaft and an inner circumference of the hollow motor so as to arrow relative movement of the input shaft and a rotor of the hollow motor in an axis direction hut to restrict relative movement of the input shaft and the rotor of the hollow motor in a rotation direction.
- the engagement structure between the input shaft and the rotor of the hollow motor relative rotational movement of the input shaft and the rotor of the hollow motor, but allows relative axial movement of the input shaft and the rotor of the hollow motor. It is therefore possible to mount the hollow motor in the form of a motor assembly to the vehicle body and improve the assembling workability of the power steering device.
- FIG. 1 is a vertical section view of a power steering device according to a first embodiment of the present invention.
- FIG. 2 is an enlarged section view of the vicinity of a hollow motor in the power steering device of FIG. 1 .
- FIG. 3( a ) is an enlarged section view of the vicinity of engagement between an input shaft and a rotor of the hollow motor in the power steering device of FIG. 1 ; and FIG. 3( b ) is a section view taken along line A-A of FIG. 3( a ).
- FIG. 4 is a system configuration diagram of the power steering device of FIG. 1 .
- FIG. 5 is a system configuration diagram of the hollow motor of FIG. 2 .
- FIG. 6 is an exploded section view showing how to assembling the hollow motor of FIG. 2 .
- FIG. 7 is an exploded section view showing how to assembling the power steering device of FIG. 1 .
- FIG. 8 is an enlarged section view corresponding to FIG. 2 but showing a hollow motor in a power steering device according to a second embodiment of the present invention.
- FIG. 9( a ) is an enlarged section view of the vicinity of engagement between an input shaft and a rotor of the hollow motor in the power steering device of FIG. 8 ; and FIG. 9( b ) is a section view taken along line B-B of FIG. 9( a ).
- FIG. 10 is an enlarged section view corresponding to FIG. 2 but showing a hollow motor in a power steering device according to a third embodiment of the present invention.
- FIG. 11( a ) is an enlarged section view of the vicinity of engagement between an input shaft and a rotor of the follow motor in the power steering device of FIG. 10 ; and FIG. 11( b ) is a section view taken along line B-B of FIG. 11( a ).
- FIGS. 1 to 7 show the power steering device according to the first embodiment of the present invention.
- the power steering device includes: a housing 3 ; an input shaft 11 having one end portion coupled to a steering wheel and the other end portion accommodated in the housing 3 ; an output shaft 12 totally accommodated in the housing 3 and coupled at one end portion thereof to the other end portion of the input shaft 11 through a torsion bar 10 ; a substantially cylindrical piston 16 disposed on the outer circumference of the other end portion of the output shaft 12 ; a sector shaft 17 coupled to steerable vehicle wheels (not shown) so as to steer the steerable vehicle wheels by axial movement of the piston 16 ; a pair of hydraulic pressure chambers P 1 and P 2 defined in the housing 3 by the piston 16 ; a power cylinder 18 for generating an assist torque to assist a steering torque; a rotary valve 19 disposed between the input and output shafts 11 and 12 so as to selectively supply a hydraulic fluid from a hydraulic pressure source (such as pump; not shown) to the hydraulic pressure chamber
- a main body of the power steering device (simply referred to as “device body DB”), which constitutes a steering system, and a cylindrical rotor 31 of the hollow motor 30 are herein arranged and fitted around the outer circumference of the one end portion of the input shaft 1 .
- the housing 3 has a cylindrical shape with one end open and the other end closed and includes a first housing member 14 defining therein the hydraulic pressure chambers P 1 and P 2 and a second housing member 15 attached to close an open end of the first housing member 14 and accommodating therein the rotary valve 19 .
- the housing members 14 and 15 are fixed to each other by a plurality of bolts (not shown) at predetermined circumferential positions.
- the first housing member 14 has, formed therein, a cylinder constituting part 14 a extending in a direction of a rotation axis Z of the input and output shafts 11 and 12 and a shaft accommodating part 14 b extending substantially perpendicular to the cylinder constituting part 14 a with a portion of the shaft accommodating pan 14 b facing the cylinder constituting part 14 a .
- the piston 16 is relatively movably disposed around the outer circumference of the other end portion of the output shaft 11 via a ball screw mechanism 20 .
- the hydraulic pressure chambers P 1 and P 2 are defined by the piston 16 in one end side and the other end side of the cylinder accommodating part 14 a , respectively.
- the sector shaft 17 is disposed and coupled at one end portion thereof to the piston 16 and at the other end portion thereof to the steerable vehicle wheels via pitman arms.
- Teeth 16 a and 17 a are formed on outer circumferential portions of the piston 16 and the sector shaft 17 , respectively, so as to be engageable with each other.
- the sector shaft 17 is rotated with axial movement of the piston 16 so as to pull the pitman arms in a vehicle width direction and thereby change the direction of the steerable vehicle wheels.
- the hydraulic fluid is introduced from the first hydraulic pressure room P 1 to the shaft accommodating part 14 h for lubrication of the teeth 16 a and 17 a.
- a shaft insertion hole 15 a is formed in an inner circumferential side of the second housing member 16 .
- a diameter of the shaft insertion hole 15 a is stepwisely reduced from one end to the other end in the direction of the rotation axis Z.
- the other end portion of the input shaft 11 and the one end portion of the output shaft 12 are arranged to overlap each other with the torsion bar 10 being disposed therebetween.
- the rotary valve 19 is situated in the overlap region between the input and output shafts 11 and 12 .
- the introduction port 21 is connected to the hydraulic pressure source via an introduction passage so as to externally introduce the hydraulic fluid through a first supply/drain passage L 1 of the one end portion (overlap region) of the output shaft 12 .
- the supply/drain port 22 is used to supply or drain the hydraulic fluid to or from the second hydraulic fluid chamber P 2 through a radially outwardly extending second supply/drain passage L 2 .
- the discharge port 23 are connected to a reservoir tank via a discharge passage so as to discharge the hydraulic fluid from the respective hydraulic pressure chambers P 1 and P 2 .
- the rotary valve 19 is kept open to permit communication between the introduction port 21 and the discharge port 23 when the steering wheel is in a neutral position. During steering operation, the rotary valve 19 is opened at one side and closed at the other side according to relative rotation of the input and output shafts 11 and 12 .
- the above-configured power steering device operates as follows.
- the hydraulic fluid is pressurized and supplied from the hydraulic pressure source to either one of the hydraulic pressure chambers P 1 and P 2 through the rotary valve 19 depending on the steering direction.
- the hydraulic fluid is discharged, by an amount (excess amount) corresponding to the supply amount, from the other of the hydraulic pressure chambers P 1 and P 2 to the reservoir tank (not shown).
- the piston 16 is hydraulically actuated so that the assist torque is applied to the sector shaft 17 based on the hydraulic pressure exerted on the piston 16 .
- the hollow motor 30 is in the form of a so-called “three-phase alternating current type brushless motor”. As shown in FIGS. 1 and 2 , the rotor 31 of the hollow motor 30 is connected by the after-mentioned key connection to the outer circumference of the one end portion of the input shaft 11 exposed outside the housing 13 .
- the hollow motor 30 includes, in addition to the rotor 31 , a stator 32 disposed around the outer circumference of the rotor 31 with a slight radial clearance being left therebetween.
- the rotor 31 and the stator 32 constitute a motor element.
- the hollow motor 30 further includes a cylindrical motor housing 33 accommodating therein the motor element and fixed at one end portion thereof to the housing 13 , first and second bearings B 1 and B 2 disposed in the motor housing 33 and rotatably supporting one end portion and the other end portion of the rotor 31 , a resolver 36 accommodated in an open cylindrical resolver accommodating part 34 b of the other end portion of the motor housing 33 so as to detect a rotational position of the input shaft 11 and a cover member 37 covering an open end (outer end opening) of the resolver accommodating part 34 b so as to prevent the entry of moisture and dust particles from the outside.
- the motor housing 33 is made of a predetermined metal material such as aluminum alloy and consists of two separate members: a first motor housing member 34 that serves as a housing body accommodating the motor element in one end portion thereof and the resolver 36 in the other end portion thereof; and a second motor housing member 35 that closes one end opening of the first motor housing member 34 and, at the same time, serves as a connector for connection to the housing 13 .
- the first motor housing member 34 has a motor element accommodating part 34 a formed in the one end portion thereof for accommodation of the motor element.
- the resolver accommodating part 34 b is formed on the other end portion of the first motor housing member 34 for accommodation of the resolver 36 .
- These accommodating parts 34 a and 34 b are separated by a partition wall 38 .
- a shaft insertion hole 38 a is formed through the center of the partition wall 38 .
- Radially extending fixing parts 34 c are formed at predetermined circumferential positions on the one end portion of the first motor housing member 34 .
- the first motor housing member 34 is fixed to an inner end surface of the second motor housing member 35 by a plurality of bolts 24 through the fixing parts 34 c , while both of the input shaft 11 and the other end portion (connection member 39 ) of the rotor 31 disposed around the input, shaft 11 are inserted in the shaft insertion hole 38 a.
- the motor element accommodating part 34 a is stepwisely reduced in diameter toward the partition wall 38 .
- the stator 32 is arranged and accommodated within the motor element accommodating part 34 a in abutment with a middle stepped region of the motor element accommodating part 34 a .
- the stator 32 is fixed to the motor element accommodating part 34 a by predetermined means such as shrinkage fitting.
- a cylindrical first bearing accommodating pan 38 b is formed on an edge of the shaft insertion hole 38 a in one surface (wall surface) of the partition wall 38 facing the motor element accommodating part 34 a for accommodation of the first bearing B 1 .
- a resolver receiving part 38 c is formed in the other wall surface of the partition wall 38 by enlargement of an edge of the shaft insertion hole 38 a .
- the resolver accommodating part 34 b is made integral with the resolver receiving part 38 c .
- the whole of the resolver 36 is arranged and accommodated within the resolver accommodating part 34 b with a resolver stator 36 b being axially partially fitted in the resolver receiving part 38 c and a resolver rotor 36 a being disposed radially inside the resolver rotor 36 b and fitted around the rotor 31 (connection member 39 ).
- the second motor housing member 35 has a substantially plate shape with some projections and depressions.
- a shaft insertion hole 35 a is formed through the center of the second motor housing member 35 .
- Both of the input shaft 11 and the other end part (connection member 39 ) of the rotor 31 disposed around the input shaft 11 are inserted in the shaft insertion hole 35 a .
- Protruding fixing parts 35 b are formed at predetermined circumferential positions on the outer circumference of the second motor housing member 35 .
- the second motor housing member 35 is fixed together with the first motor housing member 34 by the bolts 24 through the fixing parts 35 b.
- a protruding portion 15 c is formed on an outer end surface of the second housing member 15 , whereas a recessed portion 35 c is formed in the center of an outer end surface of the second motor housing member 35 .
- the hollow motor 30 and the rotary valve 19 can be placed in position relative to each other by engagement of the protruding portion 15 c and the recessed portion 35 c .
- a cylindrical second bearing accommodating part 35 d is formed on an edge of the shaft insertion hole 35 a in an inner surface of the recessed portion 35 c for accommodation of the second bearing B 2 .
- the rotor 31 includes a cylindrical connection member 39 fitted around and connected to the outer circumference of the one end portion of the input shaft 11 exposed outside from the housing 13 so that the connection member 39 can rotate together with the input shaft 11 .
- the rotor 31 also includes a rotor core 31 a made of a magnetic material and disposed around the outer circumference of the connection member 39 and a plurality of magnets 31 b joined to the outer circumference of the rotor core 31 a .
- the rotor 31 may be configured as an IPM motor in which the plurality of magnets 31 b are embedded in the rotor core 3 a.
- First and second small-diameter regions 39 a and 39 b of relatively small diameter are formed on both end portions of the connection member 39 and rotatably supported on the respective first and second bearings RBI and B 2 .
- a large-diameter region 39 c is formed on a portion of the connection member 39 between the small-diameter 10 t regions 39 a and 39 b .
- the rotor core 31 a is press-fitted to an outer circumferential surface of the large-diameter region 39 c.
- a region in front of the first small-diameter region 39 a is further stepwisely reduced in diameter and thereby adapted as a third small-diameter region 39 d .
- the resolver rotor 36 a is mounted to the third small-diameter region 39 d .
- the third small-diameter region 39 for mounting of the resolver rotor 36 a is set smaller in diameter than the first small-diameter region 39 a for mounting of the first bearing B 1 .
- the resolver rotor 36 a is thus made smaller in outer diameter even in a state that the resolver rotor 36 a is fitted around the connection member 39 (third small-diameter region 39 d ).
- the resolver stator 36 b arranged around the resolver rotor 36 a , is accordingly made smaller in diameter. This leads to a downsizing of the entire resolver 36 .
- connection member 39 is attached around the outer circumference of the input shaft 11 by the so-called key connection.
- the key connection is provided with an input-shaft-side engagement part and a rotor-side engagement part.
- the input-shaft-side engagement part is formed by axially cutting a recessed groove 11 a in an outer circumferential surface of the input shaft 11 and press-fitting a metal piece as a key 25 in the axial groove 11 a .
- the rotor-side engagement part is formed by axially cutting a key groove 39 e in an inner circumferential surface of the connection member 39 such that the key groove 39 extends from an opening end of the connection member 39 and overlaps in position with the entire large-diameter region 39 c .
- the key connection is established by engagement of these engagement parts.
- the key connection is not designed to fix the input shaft 11 and the rotor 31 in position by press-fitting the key 25 m the key groove 39 e as in conventional key connections.
- the dimensional relationship of the key 25 and the key groove 39 e is set such that the rotor 31 is detachable relative to the key 25 (input shaft 11 ) in the first embodiment. More specifically, the dimensional relationship of the key 25 and the key groove 39 e is set so as to eliminate unnecessary play between the key 25 and the key groove 39 e and, after disengagement of the key 25 and the key groove 39 e , easily re-engage the key 25 and the key groove 39 e with each other.
- the stator 32 includes a plurality of stator cores 32 a stacked into a circular shape and press- or shrinkage-fitted in the motor element accommodating part 34 a , teeth (not shown) formed protrudingly on respective inner circumferential portions of the stator cores 32 a and stator coils SC (SC 1 , SC 2 ) of three phases (U phase, V phase and W phase) wound to the teeth.
- SC stator coils SC
- the stator coils SC are provided as separate first and second stator coils SC 1 and SC 2 . These coils SC 1 and SC 2 are connected to the separate control circuits 40 a and 40 b but are wound to the same teeth. There is thus provided a multiplex control circuit system with the control circuits 40 a and 40 b for one motor 30 so that, even when there occurs a failure in one of the control circuits 40 a and 40 b , the hollow motor 30 can be driven and controlled by the other of the control circuits 40 a and 40 b (see FIG. 5 ).
- the resolver rotor 36 a is equipped with a plurality of salient poles corresponding in number to counter poles of the rotor 31 and disposed around the outer circumference of the other end portion of the connection member 39 .
- a diameter RO of the resolver rotor 36 a is set smaller than inner diameters of the shaft insertion holes 38 a and 35 a of the first and second motor housing members 34 and 35 (see FIG. 6 ).
- the resolver stator 36 b is retained in the resolver accommodating part 34 b , with a slight radial clearance being left on an outer circumferential side of the resolver rotor 36 a , and thereby kept from contact with the resolver rotor 36 a .
- Sensor coils 36 c and 36 d are wound to the resolver stator 36 b and connected to the separate control circuits 40 a and 40 b.
- Each of the first and second bearings B 1 and B 2 is in the form of a ball bearing.
- at least one of the first and second bearings B 1 and B 2 is configured to restrict axial movement of the rotor 31 for stable driving of the hollow motor 30 .
- the cover member 37 is substantially plate-shaped.
- a shaft insertion hole 37 a is formed through the center of the cover member 37 .
- the other end portion of the input shaft 11 is inserted in the shaft insertion hole 37 a .
- a seal accommodating part 37 b is formed in a recessed manner around an edge of the shaft insertion hole 37 a on an inner surface of the cover member 37 .
- a seal member 26 is fitted in the seal accommodating part 37 b so as to establish a fluid-tight seal between the input shaft 11 and the cover member 37 and prevent the entry of moisture and dust particles from the outside through the shalt insertion hole 37 a.
- various support information identification means 50 such as camera that recognizes another vehicle travelling ahead or white lines on a travelling lane, car navigation system or the like, to give driving support information Ib other than the driver's steering torque Tm.
- a vehicle-mounted main ECU 51 to give vehicle driving information Id based on the detection signals of various sensors such as vehicle speed sensor, steering angle sensor and yaw rate sensor and an automatic operation ECU 52 to generate a torque commend signal St on the basis of the driving support information Ib and the vehicle driving information Id.
- the resolver 36 generates and outputs a rotation angle signal S ⁇ . Based on these signals St and S ⁇ , the motor ECU 40 performs drive control of the hollow motor 30 with the application of a control current Ce.
- the motor ECU 40 has a plurality of control circuits (two control circuits in the first embodiment), i.e., first and second control circuits 40 a and 40 b as shown in FIG. 5 .
- Each of the first and second control circuits 40 a and 40 b receives the torque commend signal St from the automatic operation ECU 52 and the rotation angle signal S ⁇ from the resolver 36 and calculates the control current Ce based on these signals St and S ⁇ . Then, the first and second control circuits 40 a and 40 b apply the control current Ce to the stator coils SC 1 and SC 2 , respectively.
- the power steering device enables not only manual steering operation in response to the driver's steering torque Tm but also, for example, in the case where the vehicle is about to deviate from the traveling lane due to dozing driving, automatic steering operation to apply the steering torque To, rotate the input shaft 11 and thereby let the vehicle keep travelling in the travelling lane by drive control of the hollow motor 30 based on the driving support information Ib from the support information identification means 50 ) and the vehicle driving information Id from the sensors as shown in FIGS. 1 and 4 .
- the energization and drive control of the hollow motor 30 is performed during steering as well as during straight driving. Namely, the hollow motor 30 is driven and controlled in both of the case where the steering torque is generated for left or right steering and the case where the rotation of the input shaft 11 is restricted by generation of a steering retaining torque.
- the device body DB of the power steering device is assembled as follows.
- the input shaft 11 and the output shaft 12 are coupled to each other through the torsion bar and thereby combined as a shaft assembly.
- the piston 16 is coupled to one end portion of the shaft assembly.
- the other end portion of the shaft assembly is inserted and mounted in the second housing member 15 via a bearing 27 .
- the one end portion of the input shaft 11 to which the piston 16 is coupled is arranged in the first housing member 14 .
- the second housing member 15 is fitted and fixed into the first housing member 14 .
- the sector shaft 17 is also arranged in the first housing member 14 so as to bring the teeth 16 a and 17 a into engagement with each other.
- the hollow motor 30 is assembled as follows.
- the stator cores 32 a to which the stator coil SC is wound is fitted to an inner circumferential surface of the first motor housing member 34 .
- the rotor core 31 a is fitted to the outer circumferential surface of the large-diameter region 39 c of the connection member 39 .
- the first bearing B 1 and the recover rotor 36 a are then fitted around outer circumferential surfaces of the first and third small-diameter regions 39 a and 39 d of the connection member 39 , respectively.
- the second bearing B 1 is also fitted around an outer circumferential surface of the second small-diameter region 39 b of the connection member 39 .
- the rotor 31 is inserted from the side of the first small-diameter region 39 a in an inner circumferential side of the stator 32 , which has been arranged in the first motor housing member 34 , and mounted in the first motor housing member 34 via the first hearing B 1 .
- the outer diameter RO of the resolver rotor 36 a is set relatively large relative to the inner diameters R 1 and R 2 of the shaft insertion holes 38 a and 35 a of the first and second motor housing members 34 and 35 .
- the rotor 31 can be thus arranged and accommodated in the motor housing 33 in the state of the resolver rotor 36 a being mounted to the rotor 31 (connection member 39 ). It is thus possible in the first embodiment to improve the assembling workability of the power steering device as compared to the case of mounting the resolver rotor 36 a to the rotor 31 after arranging and accommodating the rotor 31 in the motor housing 33 .
- the one end of the first motor housing member 34 is closed by the second motor housing member 35 .
- the resolver stator 36 b is inserted in the first motor housing member 34 and disposed in the resolver receiving part 38 .
- the other end of the first motor housing member 34 is closed by the cover member 37 .
- the power steering device is completed by fixing the key 25 to the input shaft 11 and, after the operational test of the hollow motor 30 , fitting the rotor 31 of the hollow motor 30 around the end portion of the input shaft 11 and thereby mounting the assembly of the hollow motor 30 to the housing 13 (second housing member 15 ) as shown in FIG. 7 .
- the hollow motor 30 is fitted around the outer circumference of the input shaft 11 by, while inserting the end portion of the input shaft 11 in the inner circumference of the connection member 39 , engaging the key 25 of the outer circumference of the input shaft 11 in the key groove 39 e of the inner circumference of the rotor 31 (connection member 39 ).
- the hollow motor 31 is fixed to the second housing member 15 by insertion of the bolts 24 through the fixing parts 34 c and 35 b.
- the key groove 39 e in which the key 25 is engaged is formed on a region from the open end of the connection member 39 to an axial position required for power transmission to the rotor 31 .
- the remaining regions of the input shaft 11 and the connection member 39 are fitted to each other with a minimal radial clearance being left therebetween so that, even when there occurs rattling between the engagement parts of the input shaft 11 and the connection member 39 , such rattling can be restricted by the remaining fitting regions.
- the power steering device of the first embodiment is characterized in that the key 25 and the key groove 39 e are provided on the input shaft 11 and the inner circumferential surface of the rotor 31 (connection member 39 ), respectively, so as to constitute the engagement structure for connection between the input shaft 11 and the rotor 31 .
- This key engagement structure restricts relative movement of the input shaft 11 and the rotor 31 in the rotation direction, but allows relative movement of the input shaft 11 and the rotor 31 in the axis direction. It is therefore possible in the first embodiment to mount the hollow motor 30 in the form of the motor assembly to the device body DB and improve the assembling workability of the power steering device.
- the both end portions of the rotor (connection member 39 ) are rotatably supported in the motor housing 33 by the first and second bearings B 1 and B 2 .
- the operational test can be performed on the motor 30 by itself, it is possible to increase the degree of flexibility in the assembling process of the power steering device.
- stator coil SC protrudes axially outwardly from the both ends of the rotor 31 so that there are dead space areas S 1 and S 2 formed on an inner circumferential side of the stator coil SC.
- these hearings B 1 and B 2 can be arranged in the respective dead space areas S 1 and S 2 . This makes it possible to make effective use of the space inside the hollow motor 30 and prevent an upsizing of the hollow motor 30 and, by extension, an upsizing of the power steering device.
- the first bearing B 1 can be arranged in the dead space area S 1 as the resolver 36 is located axially outside the first bearing B 1 in the hollow motor 30 . This leads to a downsizing of the power steering device by optimization of component layout.
- the resolver 36 is located on the side of the hollow motor 30 axially opposite from the rotary valve 19 in the first embodiment. This makes it possible to avoid interference between the resolver 36 and the second motor housing member 35 (recessed portion 35 c ) so that the power steering device can achieve good component layout.
- the side of the hollow motor 30 facing the rotary valve 19 i.e. the side of the hollow motor 30 fixed to the device body DB
- the second motor housing member 35 is also closed by the second motor housing member 35 .
- FIGS. 8 and 9 show the power steering device according to the second embodiment of the present invention.
- the second embodiment is different from the first embodiment in the engagement structure between the input shaft 11 and the rotor 31 (connection member 39 ).
- connection member 39 connection member 39
- an explanation will be given only of the difference of the second embodiment from the first embodiment.
- the same reference numerals are assigned to parts and portions identical to those in the first embodiment; and detailed explanations of those parts and portions are omitted herefrom.
- a male serration 41 is formed on a predetermined region of the outer circumference of the other end portion of the input shaft 11 (corresponding in position to the large-diameter region 39 c of the connection member 39 ); whereas a female serration 42 is formed on the inner circumference of the connection member 39 of the rotor 31 so as to face the male serration 41 .
- the input shaft 11 and the rotor 31 are connected to each other by engagement of these serrations 41 and 42 .
- a region of the inner circumference of the connection member 39 overlapping in position with the second small-diameter region 39 b is adapted as a flat region 43 having a predetermined inner diameter that does not interfere with the male serration 41 .
- the female serration 42 is formed only on a predetermined axial region required for torque transmission. It is thus possible to minimize the engagement area and attain ease of assembling by engagement (engagement operation) and improvement of device productivity as compared to the case of forming the female serration 42 throughout the region of insertion of the male serration 41 on the inner circumference of the connection member 39 .
- the serration connection is not designed as firm engagement such as press-fitting, but is designed to allow relatively easy movement between the input shaft 11 and the connection member 39 and thereby permit re-engagement during mounting of the motor to the device body DB so that, even when there occurs a problem after the mounting of the hollow motor 30 to the device body DB, the hollow motor 30 and the device body D 13 can be disassembled and assembled again for improvement of manufacturing yield.
- the clearance between the serrations 41 and 42 is filled with a predetermined resin material so as to prevent rattling between the serrations 41 and 42 after the assembling and attain good torque transmission while securing improvement of manufacturing yield.
- the power steering device of the second embodiment is characterized in that the input shaft 11 and the rotor 31 are connected to each other by the serration connection.
- This serration engagement structure also restricts relative movement of the input shaft 11 and the rotor 31 in the rotation direction, but allows relative movement of the input shaft 11 and the rotor 31 in the axis direction. It is therefore possible in the second embodiment to obtain the same effects as in the first embodiment.
- the serration connection of the second embodiment leads to an increase of contact area in the rotation direction so as to attain better torque transmission as compared to the key connection of the first embodiment.
- FIGS. 10 and 11 show the power steering device according to the third embodiment of the present invention.
- the third embodiment is different from the first embodiment in the engagement structure between the input shaft 11 and the rotor 31 (connection member 39 ).
- connection member 39 connection member 39
- an explanation will be given only of the difference of the third embodiment from the first embodiment.
- the same reference numerals are assigned to parts and portions identical to those in the first embodiment; and detailed explanations of those parts and portions are omitted herefrom.
- a tolerance ring TR of known type is fitted around a predetermined region of the outer circumference of the other end portion of the input shaft 11 (corresponding in position to the large-diameter region 39 c of the connection member 39 ).
- This tolerance ring TR has an annular base portion 44 and a plurality of projection portions 45 arranged on an outer circumferential surface of the base portion 44 and constitutes a torque limiter between the input shaft 11 and the rotor 31 (connection member 39 ).
- an inner circumferential surface of the base portion 44 is fitted on the outer circumferential surface of the input shaft 11 ; and respective tip end surfaces 45 a of the projection portions 45 are pressed against the inner circumferential surface 39 f of the connection member 39 with a predetermined pressure.
- a frictional force between these surfaces 39 f and 44 a the input shaft 11 and the rotor 33 are connected to rotate together with each other.
- the power steering device of the third embodiment is characterized in that the torque limiter is constituted by the tolerance ring TR to establish engagement between the input shaft 11 and the rotor 31 .
- This engagement structure also restricts relative movement of the input shaft 11 and the rotor 31 in the rotation direction, but allows relative movement of the input shaft 11 and the rotor 31 in the axis direction. It is therefore possible in the third embodiment to obtain the same effects as in the first embodiment.
- the engagement structure of the third embodiment makes it possible that, when an excessive torque is inputted from the hollow motor 30 to the input shaft 11 , the torque limiter can relieve such an excessive torque by slippage between the input shaft 11 (TR) and the connection member 39 so as to prevent the occurrence of breakage in the engagement parts of the input shaft 11 (TR) and the connection member 39 .
- the use of the tolerance ring TR makes it possible that the inner circumferential surface of the connection member 39 can be processed into a flat shape with relatively rough precision for reduction of processing cost and makes it possible to compensate for dimensional changes caused by difference in thermal expansion rate between the input shaft 11 and the connection member 39 .
- the present invention is not limited to the above-described embodiments. Although the present invention is embodied as the integral type power steering device in the above embodiments, it is feasible to apply the present invention to any other type of power steering device, such as a rack-and-pinion type power steering device for an ordinary vehicle, as long as the subject matter of the present invention, such as power cylinder 18 and rotary valve 19 (control valve) is included.
- a rack-and-pinion type power steering device for an ordinary vehicle such as power cylinder 18 and rotary valve 19 (control valve) is included.
- the configuration of the present invention has a merit that, even in the case where the hydraulic fluid is not supplied to the device body DB due to a failure in the pump as the external hydraulic pressure source or in the piping etc. between the pump and the device body DB, steering assist can be performed by drive control of the hollow motor 30 . It is thus possible to achieve further improvement in vehicle safety.
- the rotor can be effectively restricted from moving in the axis direction.
- the rotor of the hollow motor is substantially cylindrical in shape; wherein the hollow motor includes: a stator arranged around an outer circumference of the rotor; and a motor housing accommodating therein the rotor and the stator; and wherein the motor housing includes: a cylindrical member arranged radially outside the stator; and an axial end closing member closing a rotary-valve-side end of the cylindrical member.
- the motor by itself can ensure predetermined dust resistance by also closing the rotary-valve-side of the motor housing as mentioned above.
- the rotor of the hollow motor is substantially cylindrical in shape; wherein the hollow motor is in the form of a brushless motor having: a stator arranged around an outer circumference of the rotor; a motor housing accommodating therein the rotor and the stator; and a resolver arranged on an side of the rotor opposite from the rotary valve in the axis direction so as to detect a rotational position of the rotor; wherein the motor housing has a recessed engagement portion formed in a rotary-valve-side surface thereof in the axis direction so as to surround the input shaft; wherein the power steering device further comprises a valve housing part accommodating therein the rotary valve; and wherein the valve housing part has, formed on a motor-housing-side surface thereof, a protruding engagement portion engageable in the recessed engagement portion.
- the hollow motor and the rotary valve can be placed in position relative to each other by engagement of the recessed engagement portion and the protruding engagement portion. This leads to improvement in the assembling workability of the power steering device.
- the resolver is located on the side of the hollow motor axially opposite from the rotary valve so as to avoid interference between the recessed engagement portion and the resolver. This contributes to an axial dimension reduction of the power steering device.
- This engagement permits torque transmission between the hollow motor and the input shaft while allowing relative axial movement of the hollow motor and the input shaft.
- the input shaft and the rotor can be prevented from rattling so as to attain good torque transmission.
- both of the engagement parts can be protected from breakage even during input of an excessive torque.
- the rotor of the hollow motor is substantially cylindrical in shape; wherein the hollow motor includes a plurality of stator elements having respective coils wound around the outer circumference of the rotor; and wherein the power steering device further comprises different energization circuits to which the coils of the stator elements are connected, respectively.
- the multiplex control circuit system can be constituted without the use of a plurality of motors.
- the rotor of the hollow motor is substantially cylindrical in shape; and wherein the hollow motor includes: a stator arranged around an outer circumference of the rotor; a motor housing accommodating therein the rotor and the stator; and first and second bearings disposed in the motor housing and supporting the rotor.
- the motor by itself can be subjected to operational test such as calibration. This leads to a higher degree of flexibility in the assembling process of the power steering device.
- both of the bearings can be arranged in so-called dead spaces between the small-diameter regions of the rotor and the stator so as to prevent an upsizing of the power steering device.
- the first bearing can be arranged in the dead space so as to allow optimization of component layout for downsizing of the power steering device.
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Abstract
Description
- The present invention relates to a power steering device for hydraulically assisting a driver's steering force and, more particularly, to a power steering device having a hydraulic control rotary valve driven by a motor to perform an automatic steering function.
- There is conventionally known a power steering device with an automatic steering function as disclosed in
e.g. Patent Document 1. - This power steering device is configured as a rack-and-pinion type hydraulic power steering device including an input shaft coupled to a steering wheel, an output shaft relatively rotatably coupled to the input shaft through a torsion bar, a rotary valve arranged at a position between the input shall and the output shaft on the outer circumference of a base end portion of the input shaft and a hollow motor arranged on the outer circumference of a front end portion of the input shaft.
- In such a configuration, the rotary valve is opened in response to a driver's steering torque so as to generate a steering assist torque during normal operation mode. During automatic operation mode, by contrast, the rotary valve is opened by the application of a drive torque of the hollow motor under the control of an ECU so as to generate a steering assist torque for automatic steering operation.
- Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-69767
- However, the above conventional power steering device has a problem of poor assembling workability because the hollow motor and the device body are integrated to each other. This results in a deterioration of productivity and a steep rise of manufacturing cost.
- In view of the foregoing conventional circumstances, the present invention has been made to provide a power steering device having improved assembling workability.
- According to the present invention, there is provided a power steering device, comprising: an input shaft rotated in response to steering operation of a steering wheel; an output shaft coupled to the input shaft through a torsion bar; a power cylinder having a pair of hydraulic pressure chambers defined by a piston to generate a steering assist force based on hydraulic pressures in the hydraulic pressure chambers; a rotary valve that selectively supplies hydraulic fluid from an external hydraulic pressure source to the pair of hydraulic pressure chambers in accordance with relative rotation of the input shaft and the output shaft; a hollow motor arranged to surround at least an axial portion of the input shaft and control rotation of the input shaft based on vehicle driving conditions; and input-shaft-side and rotor-side engagement parts arranged between an outer circumference of the input shaft and an inner circumference of the hollow motor so as to arrow relative movement of the input shaft and a rotor of the hollow motor in an axis direction hut to restrict relative movement of the input shaft and the rotor of the hollow motor in a rotation direction.
- In the present invention, the engagement structure between the input shaft and the rotor of the hollow motor relative rotational movement of the input shaft and the rotor of the hollow motor, but allows relative axial movement of the input shaft and the rotor of the hollow motor. It is therefore possible to mount the hollow motor in the form of a motor assembly to the vehicle body and improve the assembling workability of the power steering device.
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FIG. 1 is a vertical section view of a power steering device according to a first embodiment of the present invention. -
FIG. 2 is an enlarged section view of the vicinity of a hollow motor in the power steering device ofFIG. 1 . -
FIG. 3( a) is an enlarged section view of the vicinity of engagement between an input shaft and a rotor of the hollow motor in the power steering device ofFIG. 1 ; andFIG. 3( b) is a section view taken along line A-A ofFIG. 3( a). -
FIG. 4 is a system configuration diagram of the power steering device ofFIG. 1 . -
FIG. 5 is a system configuration diagram of the hollow motor ofFIG. 2 . -
FIG. 6 is an exploded section view showing how to assembling the hollow motor ofFIG. 2 . -
FIG. 7 is an exploded section view showing how to assembling the power steering device ofFIG. 1 . -
FIG. 8 is an enlarged section view corresponding toFIG. 2 but showing a hollow motor in a power steering device according to a second embodiment of the present invention. -
FIG. 9( a) is an enlarged section view of the vicinity of engagement between an input shaft and a rotor of the hollow motor in the power steering device ofFIG. 8 ; andFIG. 9( b) is a section view taken along line B-B ofFIG. 9( a). -
FIG. 10 is an enlarged section view corresponding toFIG. 2 but showing a hollow motor in a power steering device according to a third embodiment of the present invention. -
FIG. 11( a) is an enlarged section view of the vicinity of engagement between an input shaft and a rotor of the follow motor in the power steering device ofFIG. 10 ; andFIG. 11( b) is a section view taken along line B-B ofFIG. 11( a). - Hereinafter, embodiments of the present invention will be described below in detail with reference to the drawings. By way of example, the following embodiments each refer to an integrated type power steering device suitable for use in a large vehicle.
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FIGS. 1 to 7 show the power steering device according to the first embodiment of the present invention. As shown inFIG. 1 , the power steering device includes: a housing 3; aninput shaft 11 having one end portion coupled to a steering wheel and the other end portion accommodated in the housing 3; anoutput shaft 12 totally accommodated in the housing 3 and coupled at one end portion thereof to the other end portion of theinput shaft 11 through atorsion bar 10; a substantiallycylindrical piston 16 disposed on the outer circumference of the other end portion of theoutput shaft 12; asector shaft 17 coupled to steerable vehicle wheels (not shown) so as to steer the steerable vehicle wheels by axial movement of thepiston 16; a pair of hydraulic pressure chambers P1 and P2 defined in the housing 3 by thepiston 16; apower cylinder 18 for generating an assist torque to assist a steering torque; arotary valve 19 disposed between the input andoutput shafts output shafts hollow motor 30 for applying a torque to theinput shaft 11 for automatic steering operation as will be explained later; and amotor ECU 40 having a plurality of control circuits 40 a and 40 b (seeFIG. 5 ) to perform drive control of thehollow motor 30 based on driving conditions of the vehicle. A main body of the power steering device (simply referred to as “device body DB”), which constitutes a steering system, and acylindrical rotor 31 of thehollow motor 30 are herein arranged and fitted around the outer circumference of the one end portion of theinput shaft 1. - The housing 3 has a cylindrical shape with one end open and the other end closed and includes a
first housing member 14 defining therein the hydraulic pressure chambers P1 and P2 and asecond housing member 15 attached to close an open end of thefirst housing member 14 and accommodating therein therotary valve 19. Thehousing members - The
first housing member 14 has, formed therein, acylinder constituting part 14 a extending in a direction of a rotation axis Z of the input andoutput shafts shaft accommodating part 14 b extending substantially perpendicular to thecylinder constituting part 14 a with a portion of theshaft accommodating pan 14 b facing thecylinder constituting part 14 a. In thecylinder constituting pan 14 a, thepiston 16 is relatively movably disposed around the outer circumference of the other end portion of theoutput shaft 11 via aball screw mechanism 20. Further, the hydraulic pressure chambers P1 and P2 are defined by thepiston 16 in one end side and the other end side of thecylinder accommodating part 14 a, respectively. In theshaft accommodating part 14 b, thesector shaft 17 is disposed and coupled at one end portion thereof to thepiston 16 and at the other end portion thereof to the steerable vehicle wheels via pitman arms. - Teeth 16 a and 17 a are formed on outer circumferential portions of the
piston 16 and thesector shaft 17, respectively, so as to be engageable with each other. By engagement of theseteeth 16 a and 17 a, thesector shaft 17 is rotated with axial movement of thepiston 16 so as to pull the pitman arms in a vehicle width direction and thereby change the direction of the steerable vehicle wheels. At this time, the hydraulic fluid is introduced from the first hydraulic pressure room P1 to the shaft accommodating part 14 h for lubrication of theteeth 16 a and 17 a. - A shaft insertion hole 15 a is formed in an inner circumferential side of the
second housing member 16. A diameter of the shaft insertion hole 15 a is stepwisely reduced from one end to the other end in the direction of the rotation axis Z. In the shaft insertion hole 15 a, the other end portion of theinput shaft 11 and the one end portion of theoutput shaft 12 are arranged to overlap each other with thetorsion bar 10 being disposed therebetween. Therotary valve 19 is situated in the overlap region between the input andoutput shafts - There are formed, at predetermined axial positions in the diameter-reduced other end portion of the shaft insertion hole 15 a, an
introduction port 21, a supply/drain port 22 and adischarge port 23. Theintroduction port 21 is connected to the hydraulic pressure source via an introduction passage so as to externally introduce the hydraulic fluid through a first supply/drain passage L1 of the one end portion (overlap region) of theoutput shaft 12. The supply/drain port 22 is used to supply or drain the hydraulic fluid to or from the second hydraulic fluid chamber P2 through a radially outwardly extending second supply/drain passage L2. Thedischarge port 23 are connected to a reservoir tank via a discharge passage so as to discharge the hydraulic fluid from the respective hydraulic pressure chambers P1 and P2. - The
rotary valve 19 is kept open to permit communication between theintroduction port 21 and thedischarge port 23 when the steering wheel is in a neutral position. During steering operation, therotary valve 19 is opened at one side and closed at the other side according to relative rotation of the input andoutput shafts - The above-configured power steering device operates as follows. When the steering wheel is steered, the hydraulic fluid is pressurized and supplied from the hydraulic pressure source to either one of the hydraulic pressure chambers P1 and P2 through the
rotary valve 19 depending on the steering direction. Simultaneously, the hydraulic fluid is discharged, by an amount (excess amount) corresponding to the supply amount, from the other of the hydraulic pressure chambers P1 and P2 to the reservoir tank (not shown). As a result, thepiston 16 is hydraulically actuated so that the assist torque is applied to thesector shaft 17 based on the hydraulic pressure exerted on thepiston 16. - The
hollow motor 30 is in the form of a so-called “three-phase alternating current type brushless motor”. As shown inFIGS. 1 and 2 , therotor 31 of thehollow motor 30 is connected by the after-mentioned key connection to the outer circumference of the one end portion of theinput shaft 11 exposed outside thehousing 13. Thehollow motor 30 includes, in addition to therotor 31, astator 32 disposed around the outer circumference of therotor 31 with a slight radial clearance being left therebetween. Herein, therotor 31 and thestator 32 constitute a motor element. Thehollow motor 30 further includes acylindrical motor housing 33 accommodating therein the motor element and fixed at one end portion thereof to thehousing 13, first and second bearings B1 and B2 disposed in themotor housing 33 and rotatably supporting one end portion and the other end portion of therotor 31, aresolver 36 accommodated in an open cylindricalresolver accommodating part 34 b of the other end portion of themotor housing 33 so as to detect a rotational position of theinput shaft 11 and acover member 37 covering an open end (outer end opening) of theresolver accommodating part 34 b so as to prevent the entry of moisture and dust particles from the outside. - The
motor housing 33 is made of a predetermined metal material such as aluminum alloy and consists of two separate members: a firstmotor housing member 34 that serves as a housing body accommodating the motor element in one end portion thereof and theresolver 36 in the other end portion thereof; and a secondmotor housing member 35 that closes one end opening of the firstmotor housing member 34 and, at the same time, serves as a connector for connection to thehousing 13. - The first
motor housing member 34 has a motorelement accommodating part 34 a formed in the one end portion thereof for accommodation of the motor element. On the other hand, theresolver accommodating part 34 b is formed on the other end portion of the firstmotor housing member 34 for accommodation of theresolver 36. Theseaccommodating parts partition wall 38. Ashaft insertion hole 38 a is formed through the center of thepartition wall 38. Radially extending fixingparts 34 c are formed at predetermined circumferential positions on the one end portion of the firstmotor housing member 34. The firstmotor housing member 34 is fixed to an inner end surface of the secondmotor housing member 35 by a plurality ofbolts 24 through the fixingparts 34 c, while both of theinput shaft 11 and the other end portion (connection member 39) of therotor 31 disposed around the input,shaft 11 are inserted in theshaft insertion hole 38 a. - The motor
element accommodating part 34 a is stepwisely reduced in diameter toward thepartition wall 38. Thestator 32 is arranged and accommodated within the motorelement accommodating part 34 a in abutment with a middle stepped region of the motorelement accommodating part 34 a. In the first embodiment, thestator 32 is fixed to the motorelement accommodating part 34 a by predetermined means such as shrinkage fitting. A cylindrical firstbearing accommodating pan 38 b is formed on an edge of theshaft insertion hole 38 a in one surface (wall surface) of thepartition wall 38 facing the motorelement accommodating part 34 a for accommodation of the first bearing B1. - A
resolver receiving part 38 c is formed in the other wall surface of thepartition wall 38 by enlargement of an edge of theshaft insertion hole 38 a. Theresolver accommodating part 34 b is made integral with theresolver receiving part 38 c. The whole of theresolver 36 is arranged and accommodated within theresolver accommodating part 34 b with aresolver stator 36 b being axially partially fitted in theresolver receiving part 38 c and aresolver rotor 36 a being disposed radially inside theresolver rotor 36 b and fitted around the rotor 31 (connection member 39). - The second
motor housing member 35 has a substantially plate shape with some projections and depressions. Ashaft insertion hole 35 a is formed through the center of the secondmotor housing member 35. Both of theinput shaft 11 and the other end part (connection member 39) of therotor 31 disposed around theinput shaft 11 are inserted in theshaft insertion hole 35 a. Protruding fixingparts 35 b are formed at predetermined circumferential positions on the outer circumference of the secondmotor housing member 35. The secondmotor housing member 35 is fixed together with the firstmotor housing member 34 by thebolts 24 through the fixingparts 35 b. - A protruding portion 15 c is formed on an outer end surface of the
second housing member 15, whereas a recessedportion 35 c is formed in the center of an outer end surface of the secondmotor housing member 35. Thehollow motor 30 and therotary valve 19 can be placed in position relative to each other by engagement of the protruding portion 15 c and the recessedportion 35 c. A cylindrical second bearing accommodating part 35 d is formed on an edge of theshaft insertion hole 35 a in an inner surface of the recessedportion 35 c for accommodation of the second bearing B2. - The
rotor 31 includes acylindrical connection member 39 fitted around and connected to the outer circumference of the one end portion of theinput shaft 11 exposed outside from thehousing 13 so that theconnection member 39 can rotate together with theinput shaft 11. Therotor 31 also includes arotor core 31 a made of a magnetic material and disposed around the outer circumference of theconnection member 39 and a plurality ofmagnets 31 b joined to the outer circumference of therotor core 31 a. Alternatively, therotor 31 may be configured as an IPM motor in which the plurality ofmagnets 31 b are embedded in the rotor core 3 a. - First and second small-
diameter regions connection member 39 and rotatably supported on the respective first and second bearings RBI and B2. A large-diameter region 39 c is formed on a portion of theconnection member 39 between the small-diameter 10t regions rotor core 31 a is press-fitted to an outer circumferential surface of the large-diameter region 39 c. - A region in front of the first small-
diameter region 39 a is further stepwisely reduced in diameter and thereby adapted as a third small-diameter region 39 d. In the first embodiment, theresolver rotor 36 a is mounted to the third small-diameter region 39 d. Namely, the third small-diameter region 39 for mounting of theresolver rotor 36 a is set smaller in diameter than the first small-diameter region 39 a for mounting of the first bearing B1. Theresolver rotor 36 a is thus made smaller in outer diameter even in a state that theresolver rotor 36 a is fitted around the connection member 39 (third small-diameter region 39 d). Theresolver stator 36 b, arranged around theresolver rotor 36 a, is accordingly made smaller in diameter. This leads to a downsizing of theentire resolver 36. - As shown in
FIGS. 2 and 3 , theconnection member 39 is attached around the outer circumference of theinput shaft 11 by the so-called key connection. The key connection is provided with an input-shaft-side engagement part and a rotor-side engagement part. The input-shaft-side engagement part is formed by axially cutting a recessed groove 11 a in an outer circumferential surface of theinput shaft 11 and press-fitting a metal piece as a key 25 in the axial groove 11 a. The rotor-side engagement part is formed by axially cutting akey groove 39 e in an inner circumferential surface of theconnection member 39 such that thekey groove 39 extends from an opening end of theconnection member 39 and overlaps in position with the entire large-diameter region 39 c. The key connection is established by engagement of these engagement parts. - In the first embodiment, the key connection is not designed to fix the
input shaft 11 and therotor 31 in position by press-fitting the key 25 m thekey groove 39 e as in conventional key connections. The dimensional relationship of the key 25 and thekey groove 39 e is set such that therotor 31 is detachable relative to the key 25 (input shaft 11) in the first embodiment. More specifically, the dimensional relationship of the key 25 and thekey groove 39 e is set so as to eliminate unnecessary play between the key 25 and thekey groove 39 e and, after disengagement of the key 25 and thekey groove 39 e, easily re-engage the key 25 and thekey groove 39 e with each other. - As shown in
FIG. 2 , thestator 32 includes a plurality of stator cores 32 a stacked into a circular shape and press- or shrinkage-fitted in the motorelement accommodating part 34 a, teeth (not shown) formed protrudingly on respective inner circumferential portions of the stator cores 32 a and stator coils SC (SC1, SC2) of three phases (U phase, V phase and W phase) wound to the teeth. - The stator coils SC are provided as separate first and second stator coils SC1 and SC2. These coils SC1 and SC2 are connected to the separate control circuits 40 a and 40 b but are wound to the same teeth. There is thus provided a multiplex control circuit system with the control circuits 40 a and 40 b for one
motor 30 so that, even when there occurs a failure in one of the control circuits 40 a and 40 b, thehollow motor 30 can be driven and controlled by the other of the control circuits 40 a and 40 b (seeFIG. 5 ). - In the
resolver 36, theresolver rotor 36 a is equipped with a plurality of salient poles corresponding in number to counter poles of therotor 31 and disposed around the outer circumference of the other end portion of theconnection member 39. A diameter RO of theresolver rotor 36 a is set smaller than inner diameters of the shaft insertion holes 38 a and 35 a of the first and secondmotor housing members 34 and 35 (seeFIG. 6 ). Theresolver stator 36 b is retained in theresolver accommodating part 34 b, with a slight radial clearance being left on an outer circumferential side of theresolver rotor 36 a, and thereby kept from contact with theresolver rotor 36 a. Sensor coils 36 c and 36 d are wound to theresolver stator 36 b and connected to the separate control circuits 40 a and 40 b. - Each of the first and second bearings B1 and B2 is in the form of a ball bearing. In the first embodiment, at least one of the first and second bearings B1 and B2 is configured to restrict axial movement of the
rotor 31 for stable driving of thehollow motor 30. - The
cover member 37 is substantially plate-shaped. Ashaft insertion hole 37 a is formed through the center of thecover member 37. The other end portion of theinput shaft 11 is inserted in theshaft insertion hole 37 a. Aseal accommodating part 37 b is formed in a recessed manner around an edge of theshaft insertion hole 37 a on an inner surface of thecover member 37. Aseal member 26 is fitted in theseal accommodating part 37 b so as to establish a fluid-tight seal between theinput shaft 11 and thecover member 37 and prevent the entry of moisture and dust particles from the outside through theshalt insertion hole 37 a. - As shown in
FIG. 4 , there are provided various support information identification means 50, such as camera that recognizes another vehicle travelling ahead or white lines on a travelling lane, car navigation system or the like, to give driving support information Ib other than the driver's steering torque Tm. There are also provided a vehicle-mountedmain ECU 51 to give vehicle driving information Id based on the detection signals of various sensors such as vehicle speed sensor, steering angle sensor and yaw rate sensor and anautomatic operation ECU 52 to generate a torque commend signal St on the basis of the driving support information Ib and the vehicle driving information Id. On the other hand, theresolver 36 generates and outputs a rotation angle signal Sθ. Based on these signals St and Sθ, themotor ECU 40 performs drive control of thehollow motor 30 with the application of a control current Ce. - More specifically, the
motor ECU 40 has a plurality of control circuits (two control circuits in the first embodiment), i.e., first and second control circuits 40 a and 40 b as shown inFIG. 5 . Each of the first and second control circuits 40 a and 40 b receives the torque commend signal St from theautomatic operation ECU 52 and the rotation angle signal Sθ from theresolver 36 and calculates the control current Ce based on these signals St and Sθ. Then, the first and second control circuits 40 a and 40 b apply the control current Ce to the stator coils SC1 and SC2, respectively. - In the above configuration, the power steering device enables not only manual steering operation in response to the driver's steering torque Tm but also, for example, in the case where the vehicle is about to deviate from the traveling lane due to dozing driving, automatic steering operation to apply the steering torque To, rotate the
input shaft 11 and thereby let the vehicle keep travelling in the travelling lane by drive control of thehollow motor 30 based on the driving support information Ib from the support information identification means 50) and the vehicle driving information Id from the sensors as shown inFIGS. 1 and 4 . - Herein, the energization and drive control of the
hollow motor 30 is performed during steering as well as during straight driving. Namely, thehollow motor 30 is driven and controlled in both of the case where the steering torque is generated for left or right steering and the case where the rotation of theinput shaft 11 is restricted by generation of a steering retaining torque. - Next, the assembling process of the power steering device of the first embodiment will be explained below with reference to
FIGS. 6 and 7 . - The device body DB of the power steering device is assembled as follows. The
input shaft 11 and theoutput shaft 12 are coupled to each other through the torsion bar and thereby combined as a shaft assembly. Thepiston 16 is coupled to one end portion of the shaft assembly. The other end portion of the shaft assembly is inserted and mounted in thesecond housing member 15 via abearing 27. The one end portion of theinput shaft 11 to which thepiston 16 is coupled is arranged in thefirst housing member 14. Then, thesecond housing member 15 is fitted and fixed into thefirst housing member 14. Simultaneously with the arrangement of theinput shaft 11 and thepiston 16, thesector shaft 17 is also arranged in thefirst housing member 14 so as to bring theteeth 16 a and 17 a into engagement with each other. - Separately from the assembling of the device body DB, the
hollow motor 30 is assembled as follows. The stator cores 32 a to which the stator coil SC is wound is fitted to an inner circumferential surface of the firstmotor housing member 34. As to therotor 31, therotor core 31 a is fitted to the outer circumferential surface of the large-diameter region 39 c of theconnection member 39. The first bearing B1 and the recoverrotor 36 a are then fitted around outer circumferential surfaces of the first and third small-diameter regions connection member 39, respectively. The second bearing B1 is also fitted around an outer circumferential surface of the second small-diameter region 39 b of theconnection member 39. After that, therotor 31 is inserted from the side of the first small-diameter region 39 a in an inner circumferential side of thestator 32, which has been arranged in the firstmotor housing member 34, and mounted in the firstmotor housing member 34 via the first hearing B1. - In the first embodiment, the outer diameter RO of the
resolver rotor 36 a is set relatively large relative to the inner diameters R1 and R2 of the shaft insertion holes 38 a and 35 a of the first and secondmotor housing members rotor 31 can be thus arranged and accommodated in themotor housing 33 in the state of theresolver rotor 36 a being mounted to the rotor 31 (connection member 39). It is thus possible in the first embodiment to improve the assembling workability of the power steering device as compared to the case of mounting theresolver rotor 36 a to therotor 31 after arranging and accommodating therotor 31 in themotor housing 33. - Subsequent to the accommodation and arrangement of the motor element, the one end of the first
motor housing member 34 is closed by the secondmotor housing member 35. Theresolver stator 36 b is inserted in the firstmotor housing member 34 and disposed in theresolver receiving part 38. Then, the other end of the firstmotor housing member 34 is closed by thecover member 37. With this, the assembling of thehollow motor 30 is completed. After the completion of such motor assembling, thehollow motor 30 is driven for its operational test. - Finally, the power steering device is completed by fixing the key 25 to the
input shaft 11 and, after the operational test of thehollow motor 30, fitting therotor 31 of thehollow motor 30 around the end portion of theinput shaft 11 and thereby mounting the assembly of thehollow motor 30 to the housing 13 (second housing member 15) as shown inFIG. 7 . More specifically, thehollow motor 30 is fitted around the outer circumference of theinput shaft 11 by, while inserting the end portion of theinput shaft 11 in the inner circumference of theconnection member 39, engaging the key 25 of the outer circumference of theinput shaft 11 in thekey groove 39 e of the inner circumference of the rotor 31 (connection member 39). After the protruding portion 15 c of thesecond housing member 15 is engaged in the recessedportion 35 c of the secondmotor housing member 35, thehollow motor 31 is fixed to thesecond housing member 15 by insertion of thebolts 24 through the fixingparts - In the first embodiment, the
key groove 39 e in which the key 25 is engaged is formed on a region from the open end of theconnection member 39 to an axial position required for power transmission to therotor 31. The remaining regions of theinput shaft 11 and theconnection member 39 are fitted to each other with a minimal radial clearance being left therebetween so that, even when there occurs rattling between the engagement parts of theinput shaft 11 and theconnection member 39, such rattling can be restricted by the remaining fitting regions. - As described above, the power steering device of the first embodiment is characterized in that the key 25 and the
key groove 39 e are provided on theinput shaft 11 and the inner circumferential surface of the rotor 31 (connection member 39), respectively, so as to constitute the engagement structure for connection between theinput shaft 11 and therotor 31. This key engagement structure restricts relative movement of theinput shaft 11 and therotor 31 in the rotation direction, but allows relative movement of theinput shaft 11 and therotor 31 in the axis direction. It is therefore possible in the first embodiment to mount thehollow motor 30 in the form of the motor assembly to the device body DB and improve the assembling workability of the power steering device. - In the assembly of the
hollow motor 30, the both end portions of the rotor (connection member 39) are rotatably supported in themotor housing 33 by the first and second bearings B1 and B2. As the operational test can be performed on themotor 30 by itself, it is possible to increase the degree of flexibility in the assembling process of the power steering device. In other words, it is feasible to assemble thehollow motor 30 separately from the device body DB or feasible to purchase and use thehollow motor 30 as the operational test can be performed on thehollow motor 30 by itself. This contributes to a reduction of device manufacturing cost. - Further, the stator coil SC protrudes axially outwardly from the both ends of the
rotor 31 so that there are dead space areas S1 and S2 formed on an inner circumferential side of the stator coil SC. To support the both end portions of therotor 31 by the first and second bearings B1 and B2, these hearings B1 and B2 can be arranged in the respective dead space areas S1 and S2. This makes it possible to make effective use of the space inside thehollow motor 30 and prevent an upsizing of thehollow motor 30 and, by extension, an upsizing of the power steering device. - In the first embodiment, the first bearing B1 can be arranged in the dead space area S1 as the
resolver 36 is located axially outside the first bearing B1 in thehollow motor 30. This leads to a downsizing of the power steering device by optimization of component layout. - Furthermore, the
resolver 36 is located on the side of thehollow motor 30 axially opposite from therotary valve 19 in the first embodiment. This makes it possible to avoid interference between theresolver 36 and the second motor housing member 35 (recessedportion 35 c) so that the power steering device can achieve good component layout. - In the assembly of the
hollow motor 30, the side of thehollow motor 30 facing the rotary valve 19 (i.e. the side of thehollow motor 30 fixed to the device body DB) is also closed by the secondmotor housing member 35. Thus, themotor 30 by itself can ensure predetermined dust resistance. -
FIGS. 8 and 9 show the power steering device according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in the engagement structure between theinput shaft 11 and the rotor 31 (connection member 39). Hereinafter, an explanation will be given only of the difference of the second embodiment from the first embodiment. In the second embodiment, the same reference numerals are assigned to parts and portions identical to those in the first embodiment; and detailed explanations of those parts and portions are omitted herefrom. - In the second embodiment, a
male serration 41 is formed on a predetermined region of the outer circumference of the other end portion of the input shaft 11 (corresponding in position to the large-diameter region 39 c of the connection member 39); whereas afemale serration 42 is formed on the inner circumference of theconnection member 39 of therotor 31 so as to face themale serration 41. Theinput shaft 11 and therotor 31 are connected to each other by engagement of theseserrations - A region of the inner circumference of the
connection member 39 overlapping in position with the second small-diameter region 39 b is adapted as aflat region 43 having a predetermined inner diameter that does not interfere with themale serration 41. Namely, thefemale serration 42 is formed only on a predetermined axial region required for torque transmission. It is thus possible to minimize the engagement area and attain ease of assembling by engagement (engagement operation) and improvement of device productivity as compared to the case of forming thefemale serration 42 throughout the region of insertion of themale serration 41 on the inner circumference of theconnection member 39. - In the second embodiment, the serration connection is not designed as firm engagement such as press-fitting, but is designed to allow relatively easy movement between the
input shaft 11 and theconnection member 39 and thereby permit re-engagement during mounting of the motor to the device body DB so that, even when there occurs a problem after the mounting of thehollow motor 30 to the device body DB, thehollow motor 30 and the device body D13 can be disassembled and assembled again for improvement of manufacturing yield. - In such engagement structure, the clearance between the
serrations serrations - As described above, the power steering device of the second embodiment is characterized in that the
input shaft 11 and therotor 31 are connected to each other by the serration connection. This serration engagement structure also restricts relative movement of theinput shaft 11 and therotor 31 in the rotation direction, but allows relative movement of theinput shaft 11 and therotor 31 in the axis direction. It is therefore possible in the second embodiment to obtain the same effects as in the first embodiment. - In particular, the serration connection of the second embodiment leads to an increase of contact area in the rotation direction so as to attain better torque transmission as compared to the key connection of the first embodiment.
-
FIGS. 10 and 11 show the power steering device according to the third embodiment of the present invention. The third embodiment is different from the first embodiment in the engagement structure between theinput shaft 11 and the rotor 31 (connection member 39). Hereinafter, an explanation will be given only of the difference of the third embodiment from the first embodiment. In the third embodiment, the same reference numerals are assigned to parts and portions identical to those in the first embodiment; and detailed explanations of those parts and portions are omitted herefrom. - In the third embodiment, a tolerance ring TR of known type is fitted around a predetermined region of the outer circumference of the other end portion of the input shaft 11 (corresponding in position to the large-
diameter region 39 c of the connection member 39). This tolerance ring TR has anannular base portion 44 and a plurality ofprojection portions 45 arranged on an outer circumferential surface of thebase portion 44 and constitutes a torque limiter between theinput shaft 11 and the rotor 31 (connection member 39). - More specifically, an inner circumferential surface of the
base portion 44 is fitted on the outer circumferential surface of theinput shaft 11; and respective tip end surfaces 45 a of theprojection portions 45 are pressed against the innercircumferential surface 39 f of theconnection member 39 with a predetermined pressure. By a frictional force between thesesurfaces 39 f and 44 a, theinput shaft 11 and therotor 33 are connected to rotate together with each other. - As described above, the power steering device of the third embodiment is characterized in that the torque limiter is constituted by the tolerance ring TR to establish engagement between the
input shaft 11 and therotor 31. This engagement structure also restricts relative movement of theinput shaft 11 and therotor 31 in the rotation direction, but allows relative movement of theinput shaft 11 and therotor 31 in the axis direction. It is therefore possible in the third embodiment to obtain the same effects as in the first embodiment. - In particular, the engagement structure of the third embodiment makes it possible that, when an excessive torque is inputted from the
hollow motor 30 to theinput shaft 11, the torque limiter can relieve such an excessive torque by slippage between the input shaft 11 (TR) and theconnection member 39 so as to prevent the occurrence of breakage in the engagement parts of the input shaft 11 (TR) and theconnection member 39. - Furthermore, the use of the tolerance ring TR makes it possible that the inner circumferential surface of the
connection member 39 can be processed into a flat shape with relatively rough precision for reduction of processing cost and makes it possible to compensate for dimensional changes caused by difference in thermal expansion rate between theinput shaft 11 and theconnection member 39. - The present invention is not limited to the above-described embodiments. Although the present invention is embodied as the integral type power steering device in the above embodiments, it is feasible to apply the present invention to any other type of power steering device, such as a rack-and-pinion type power steering device for an ordinary vehicle, as long as the subject matter of the present invention, such as
power cylinder 18 and rotary valve 19 (control valve) is included. - In addition, the configuration of the present invention has a merit that, even in the case where the hydraulic fluid is not supplied to the device body DB due to a failure in the pump as the external hydraulic pressure source or in the piping etc. between the pump and the device body DB, steering assist can be performed by drive control of the
hollow motor 30. It is thus possible to achieve further improvement in vehicle safety. - Hereinafter, an explanation will be given of technical ideas comprehended from the above embodiments but not described in the following claims.
- (a) The power steering device according to claim 5, wherein a region of the rotor in which the resolver rotor is disposed is set smaller in outer diameter than a region of the rotor in which the first bearing is disposed.
- By setting the outer diameter of the rotor to a small value as mentioned above, not only the resolver rotor around the rotor but also the resolver stator around the resolver rotor can be made smaller in out diameter. This leads to a downsizing of the entire resolver.
- (b) The power steering device according to
claim 2, wherein at least one of the first and second bearings is in the form of a ball hearing adapted to restrict movement of the rotor in the axis direction. - In such a case, the rotor can be effectively restricted from moving in the axis direction.
- (c) The power steering device according to
claim 1, wherein the rotor of the hollow motor is substantially cylindrical in shape; wherein the hollow motor includes: a stator arranged around an outer circumference of the rotor; and a motor housing accommodating therein the rotor and the stator; and wherein the motor housing includes: a cylindrical member arranged radially outside the stator; and an axial end closing member closing a rotary-valve-side end of the cylindrical member. - The motor by itself can ensure predetermined dust resistance by also closing the rotary-valve-side of the motor housing as mentioned above.
- (d) The power steering device according to
claim 1, wherein the rotor of the hollow motor is substantially cylindrical in shape; wherein the hollow motor is in the form of a brushless motor having: a stator arranged around an outer circumference of the rotor; a motor housing accommodating therein the rotor and the stator; and a resolver arranged on an side of the rotor opposite from the rotary valve in the axis direction so as to detect a rotational position of the rotor; wherein the motor housing has a recessed engagement portion formed in a rotary-valve-side surface thereof in the axis direction so as to surround the input shaft; wherein the power steering device further comprises a valve housing part accommodating therein the rotary valve; and wherein the valve housing part has, formed on a motor-housing-side surface thereof, a protruding engagement portion engageable in the recessed engagement portion. - The hollow motor and the rotary valve can be placed in position relative to each other by engagement of the recessed engagement portion and the protruding engagement portion. This leads to improvement in the assembling workability of the power steering device.
- In addition, the resolver is located on the side of the hollow motor axially opposite from the rotary valve so as to avoid interference between the recessed engagement portion and the resolver. This contributes to an axial dimension reduction of the power steering device.
- (e) The power steering device according to
claim 1, wherein the input-shaft-side engagement part and the rotor-side engagement part are provided on only a rotary-valve-side region of the rotor in the axis direction. - In such a case, the assembling of these engagement parts can be facilitated as compared to the case where the engagement parts are provided on the entire axial region of the rotor.
- (f) The power steering device according to
claim 1, wherein the input-shaft-side engagement part and the rotor-side engagement part are formed with respective serrations and engaged with each other by the serrations. - This engagement permits torque transmission between the hollow motor and the input shaft while allowing relative axial movement of the hollow motor and the input shaft.
- (g) The power steering device according to (f), wherein there is a resin material filled in between the input-shaft-side engagement part and the rotor-side engagement part.
- By filling the resin material as mentioned above, the input shaft and the rotor can be prevented from rattling so as to attain good torque transmission.
- (h) The power steering device according to
claim 1, wherein the input-shaft-side engagement part and the rotor-side engagement part are provided on a predetermined region of the rotor in the axis direction; and wherein remaining regions of the input shaft and the rotor are formed with flat circumferential surfaces and adapted to allow contact between the flat circumferential surfaces along entire circumferences thereof. - This makes it possible that, even when there occurs rattling between the engagement parts, such rattling can be restricted by the remaining regions.
- (i) The power steering device according to
claim 1, wherein there is provided a torque limiter between the input-shaft-side engagement part and the rotor-side engagement part. - By the adoption of the torque limiter, both of the engagement parts can be protected from breakage even during input of an excessive torque.
- (j) The power steering device according to
claim 1, wherein the rotor of the hollow motor is substantially cylindrical in shape; wherein the hollow motor includes a plurality of stator elements having respective coils wound around the outer circumference of the rotor; and wherein the power steering device further comprises different energization circuits to which the coils of the stator elements are connected, respectively. - In this case, the multiplex control circuit system can be constituted without the use of a plurality of motors.
- (k) The power steering device according to claim 7, wherein the rotor of the hollow motor is substantially cylindrical in shape; and wherein the hollow motor includes: a stator arranged around an outer circumference of the rotor; a motor housing accommodating therein the rotor and the stator; and first and second bearings disposed in the motor housing and supporting the rotor.
- The motor by itself can be subjected to operational test such as calibration. This leads to a higher degree of flexibility in the assembling process of the power steering device.
- (l) The power steering device according to (k), wherein the rotor has: a large-diameter region formed at a middle thereof in the rotation axis direction of the input shaft and facing the stator; and first and second small-diameter regions formed on one side and the other side of the large-diameter region in the axis direction and made smaller in diameter than the large-diameter region; wherein the stator extends to the one side and the other side of the large-diameter region in the axis direction; wherein the first bearing is disposed between the first small-diameter region and the stator; and wherein the second bearing is disposed between the second small-diameter region and the stator.
- In this case, both of the bearings can be arranged in so-called dead spaces between the small-diameter regions of the rotor and the stator so as to prevent an upsizing of the power steering device.
- (m) The power steering device according to (l), wherein the hollow motor is in the form of a brushless motor having a resolver to detect a rotational position of the rotor; and wherein the resolver is located outside the first bearing in the axis direction.
- As the resolver is located axially outside the first bearing, the first bearing can be arranged in the dead space so as to allow optimization of component layout for downsizing of the power steering device.
-
-
- 10: Torsion bar
- 11: Input shaft
- 12: Output shaft
- 16: Piston
- 18: Power cylinder
- 19: Rotary valve (Control valve)
- 25: Key (Input-shaft-side engagement part)
- 30: Hollow motor
- 39 e: Key groove (Rotor-side engagement part)
- 39 f: Inner circumferential surface (Rotor-side engagement part)
- 41: Male serration (Input-shaft-side engagement part)
- 42: Female serration (Rotor-side engagement pan)
- 45 a: Tip end surface of projection portion (Input-shaft-side engagement part)
- P: First hydraulic pressure room (Pair of hydraulic pressure chambers)
- P2: Second hydraulic pressure room (Pair of hydraulic pressure chambers)
Claims (20)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2012286561 | 2012-12-28 | ||
JP2012-286561 | 2012-12-28 | ||
PCT/JP2013/080990 WO2014103556A1 (en) | 2012-12-28 | 2013-11-18 | Power-steering device |
Publications (2)
Publication Number | Publication Date |
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US20150298728A1 true US20150298728A1 (en) | 2015-10-22 |
US9452777B2 US9452777B2 (en) | 2016-09-27 |
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ID=51020651
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US14/646,803 Active US9452777B2 (en) | 2012-12-28 | 2013-11-18 | Power-steering device |
Country Status (5)
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US (1) | US9452777B2 (en) |
JP (1) | JP6228929B2 (en) |
CN (1) | CN104884334B (en) |
DE (1) | DE112013006261T5 (en) |
WO (1) | WO2014103556A1 (en) |
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Also Published As
Publication number | Publication date |
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DE112013006261T5 (en) | 2015-10-01 |
CN104884334A (en) | 2015-09-02 |
JPWO2014103556A1 (en) | 2017-01-12 |
JP6228929B2 (en) | 2017-11-08 |
CN104884334B (en) | 2017-05-10 |
WO2014103556A1 (en) | 2014-07-03 |
US9452777B2 (en) | 2016-09-27 |
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